X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=arch%2Fx86%2Fmm%2Finit_64.c;h=49c274ee2fba64ea9b48713b96f814fc0afa5d23;hb=ae531c26c5c2a28ca1b35a75b39b3b256850f2c8;hp=1ff7906a9a4dbc7afa6dfdd24f274e077cd26773;hpb=94bc891b00e40cbec375feb4568780af183fd7f4;p=linux-2.6-omap-h63xx.git

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 1ff7906a9a4..49c274ee2fb 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -664,6 +664,26 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address
+ * is valid. The argument is a physical page number.
+ *
+ *
+ * On x86, access has to be given to the first megabyte of ram because that area
+ * contains bios code and data regions used by X and dosemu and similar apps.
+ * Access has to be given to non-kernel-ram areas as well, these contain the PCI
+ * mmio resources as well as potential bios/acpi data regions.
+ */
+int devmem_is_allowed(unsigned long pagenr)
+{
+	if (pagenr <= 256)
+		return 1;
+	if (!page_is_ram(pagenr))
+		return 1;
+	return 0;
+}
+
+
 static struct kcore_list kcore_mem, kcore_vmalloc, kcore_kernel,
 			 kcore_modules, kcore_vsyscall;